1. Field of the Invention
The invention relates to substituted pentaalkylchromans of the general formula: ##STR2## wherein R denotes a lower alkyl group having 1 to 4 C atoms and Hal denotes chlorine, bromine or iodine, and to a process for their preparation.
Pentaalkylchromans, in particular the tetramethyl derivatives of the general formula I, are useful intermediates for the preparation of, for example, hypolipidaemic pharmaceuticals [J. Med. Chem., 32, (1989), pp. 421 to 428].
2. Background Art
To prepare the hypolipidaemic pharmaceuticals, it was known to employ hydroxyalkylchromans of the general formula: ##STR3## as intermediates [J. Med. Chem., 32, (1989), p. 421].
According to German Offenlegungsschrift 3,010,504, these hydroxyalkylchromans are obtainable from the corresponding hydroquinone and the corresponding butenediol with only a yield of 10 percent.
According to German Offenlegungsschrift 2,364,165, it is also known to prepare the hydroxyalkylchromans in a multi-step synthesis. However, this synthesis is very costly and not suitable for the industrial reaction.